Nano computing

48. Distributed computing is also a computing system that consists of multiple
computers or processor machines connected through a network, which can be
homogeneous or heterogeneous, but run as a single system. The connectivity can
be such that the CPUs in a distributed system can be physically close together and
connected by a local network, or they can be geographically distant and connected
by a wide area network. The heterogeneity in a distributed system supports any
number of possible configurations in the processor machines, such as mainframes,
PCs, workstations, and minicomputers. The goal of distributed computing is to
make such a network work as a single computer. Distributed computing systems are
advantageous over centralized systems, because there is a support for the following
characteristic features: 1. Scalability: It is the ability of the system to be easily
expanded by adding more machines as needed, and vice versa, without affecting
the existing setup. 2. Redundancy or replication: Here, several machines can
provide the same services, so that even if one is unavailable (or failed), work does
not stop because other similar computing supports will be available.

49. • A cluster computing system consists of a set of the same or similar type of
processor machines connected using a dedicated network infrastructure.
All processor machines share resources such as a common home directory
and have a software such as a message passing interface (MPI)
implementation installed to allow programs to be run across all nodes
simultaneously. This is also a kind of HPC category. The individual
computers in a cluster can be referred to as nodes. The reason to realize a
cluster as HPC is due to the fact that the individual nodes can work
together to solve a problem larger than any computer can easily solve.
And, the nodes need to communicate with one another in order to work
cooperatively and meaningfully together to solve the problem in hand. If
we have processor machines of heterogeneous types in a cluster, this kind
of clusters become a subtype and still mostly are in the experimental or
research stage.

50. • Cloud Computing The computing trend moved toward cloud from the
concept of grid computing, particularly when large computing resources
are required to solve a single problem, using the ideas of computing power
as a utility and other allied concepts. However, the potential difference
between grid and cloud is that grid computing supports leveraging several
computers in parallel to solve a particular application, while cloud
computing supports leveraging multiple resources, including computing
resources, to deliver a unified service to the end user. In cloud computing,
the IT and business resources, such as servers, storage, network,
applications, and processes, can be dynamically provisioned to the user
needs and workload. In addition, while a cloud can provision and support a
grid, a cloud can also support nongrid environments, such as a three-tier
web architecture running on traditional or Web 2.0 applications

51. • In mobile computing, the processing (or computing) elements are small
(i.e., handheld devices) and the communication between various resources
is taking place using wireless media. Mobile communication for voice
applications (e.g., cellular phone) is widely established throughout the
world and witnesses a very rapid growth in all its dimensions including the
increase in the number of subscribers of various cellular networks. An
extension of this technology is the ability to send and receive data across
various cellular networks using small devices such as smartphones. There
can be numerous applications based on this technology; for example, video
call or conferencing is one of the important applications that people prefer
to use in place of existing voice (only) communications on mobile phones.
Mobile computing–based applications are becoming very important and
rapidly evolving with various technological advancements as it allows users
to transmit data from remote locations to other remote or fixed locations